1. Field of the Invention
The invention relates to a method for producing an antimicrobial coating on a technical surface.
2. Description of the Prior Art
Antimicrobial coatings of the above-mentioned type are used in an intrinsically known manner in food packaging materials for protecting the packed food products from attack by microorganisms such a bacteria, fungi or other germs. Perishable food products in particular can be stored for a long time in a high quality condition when packaging materials with an antimicrobial coating are used. In addition, the risk of the occurrence of pathogens on or in the packed food products is reduced.
Antimicrobial coatings typically have a carrier layer in a matrix design with active substances or inhibitors embedded therein, which, upon contact with microorganisms, kill them or inhibit or prevent their growth. At present two principles of operation of antimicrobial coatings are essentially known:
The first principle of operation is that the antimicrobial active substances and inhibitors have volatile properties and are first embedded in a carrier layer of a matrix design, but are released in time from the matrix material. The antimicrobial action therefore takes place not only in the close region above the coated surface, but the active substances and inhibitors develop their antimicrobial action throughout the packaging volume by release from the carrier layer. Suitable antimicrobial active substances for this principle of operation may be used for food applications in the European area (for example chlorine dioxide, since it is toxic, or ethanol, since it has adverse sensory properties).
The second principle of operation is significantly more widespread and is that the antimicrobial active substances and inhibitors are spatially fixed in the carrier layer in such a manner that they not able to escape from the carrier layer independently. The antimicrobial action of the active substances and inhibitors embedded in the coating material of a matrix design is developed, in particular, by contact of the food products with the antimicrobially coated surface. Here the active substances and inhibitors can diffuse through the surface of the matrix material into the surface of the food product so that the antimicrobial action of the coating is determined essentially by the diffusion kinetics.
With regard to the packing of food products with antimicrobially coated food packaging materials, a multiplicity of active substances and inhibitors, as well as release mechanisms, have been investigated in recent years. The publication: ‘Review of Antimicrobial Food Packaging’, by Paola Appendini and Joseph H. Hotchkiss, in Innovative Food Science & Emerging Technologies 3 (2002) 113-126, gives an overview of these substances.
However, the methods of the prior art for producing an antimicrobial coating suffer from the disadvantage that the coating is either technically complicated to produce, and is therefore expensive, or the raw materials used are not available in sufficient quantity or the raw materials and/or the resultant product substances do not meet the legal requirements.